Formatting Clef Changes Between Staff and Instrument Type Changes

Update: I found a workaround. Manually adjusting the vertical offset within the appearance menu for the clef itself to 2.0 places it correctly.

I'm using 4.0.1.

I am writing a piece which involves pitched instruments (in this case, alto voice) doing unpitched effects (such as snapping [plus noteheads] and sighing [slashed noteheads]). When the part switches, I would like it to change from a five-line treble clef pitched staff to a one- or two-line percussion staff with percussion clef. I know that you can't put a percussion clef on a pitched part unless you go through the symbols palette, so as a workaround I decided to change the instrument from alto to an unpitched percussion instrument so that I could use the percussion clef. When I did this, however, the new clef appeared offset, positioned so that it was centred over the top line of the staff. I would like it to be in the middle of the staff, to match the position of my single line. Is there something I'm doing wrong, or some way to fix this formatting issue so that the clef can be lined up correctly?

A few notes:
I could put the single line on the top of the staff so that it would be lined up with the percussion clef where it is, but I don't like how that looks.
I don't care about playback. I'd be happy to use a different percussion instrument if it would help.
I would normally just put X noteheads on the five-line staff, but I'm taking composition lessons and my teacher has specifically asked me to do it this way.
A picture is attached for reference. It includes my staff type change settings, which I don't think should be causing the issue, since the step offset is at zero (and doesn't seem to be changing the position of the clef anyways). The regular offset also doesn't affect the clef.
You'll also see that my dynamics are causing some formatting issues. This is less important, but if there's a way to correct their placements I wouldn't mind getting some information about that as well.

Thank you!